Gauze feeding and cut-off mechanism



April 22, 1958 c. w. MOTT GAUZE FEEDING AND CUT-OFF MECHANISM Original Filed Nov. 20, 1948 aaaT 4 Sheets-Sheet 1 IN VEN TOR.

April 1958 c. w. MOTT GAUZE FEEDING AND CUT-OFF MECHANISM Original Filed Nov. 20, 1948 4 Sheets-Sheet 2 INVENTOR. Ca]! ZW/Fi BY April 1958 c. w. MOTT 2,831,679

GAUZE FEEDING AND CUT-OFF MECHANISM Original Filed Nov. 20, 1948 4 Sheets-Sheet 3 IN V EN TOR.

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April 22, 1958 c. w. MOTT 2,831,679

GAUZE FEEDING AND CUT-OFF MECHANISM Original Filed Nov. 20, 1948 4 Sheets-Sheet 4 INVENTOR.

Car! W015i initd States 2,831,679 GAUZE FEEDING AND CUT-OFF MECHANISM Carl W. Mott, Lake Ozark, M0., assignor, by mesne assignments, to The Kendall Company, Boston, Mass., a corporation of Massachusetts 4 Claims. (Cl. 271-) This invention concerns mechanism for successively cutting end portions from a gauze strip to form gauze swatches therefrom, and more particularly concerns such an apparatus employing fingers grippable onto an end portion of a strip which is unwindable from a roll, the fingers being operable to pull successive portions from the roll attendant to it unwinding, to hold each strip end portion while it is sheared from the roll, deliver each sheared off strip portion to a place of deposit and move retractively after each delivery into position for re-engaging the fresh end portion of the roll in readiness to commence each new cycle.

This application, which is a division of my pending parent application, Serial No. 61,224, filed November 20, 1948, now Patent No. 2,709,836 issued June 7, 1955, for Machine for and Method of Making Surgical Sponges, discloses a subcombination of said machine. The machine disclosed in said parent application is operable to produce surgical sponges comprising a body of filling material within a globular-shaped sack-like jacket formed of a gauze swatch. Said machine includes a surgical sponge assembling section at which the filling material, a swatch for forming the jacket and fastening means for respectively holding the sponges fabricated are assembled.

The general object of this invention is the provision of a new and unique mechanism for forming the gauze swatch components of the surgical sponges from a gauze strip as it is unwound from a roll and delivering these swatches to the sponge assembling section of the machine for making these sponges.

Other more specific objects inherent in and encompassed by the invention are elucidated in the insuing description, the appended claims, and the annexed drawings, wherein:

Fig. 1 is a fragmentary side perspective view showing a portion of a machine for making surgical sponges, the view particularly illustrating gauze feeding and cut-off mechanism constituting a preferred embodiment of this invention.

Fig. 2 is a fragmentary perspectivev view taken from the left side of the mechanism as illustrated in Fig. 1.

Fig. 3 is a side elevational fragmentary view at reduced scale illustrating parts of the mechanism at a difierent stage of operation than shown in Fig. l and eliminating some of the parts of Fig. 1 for clarity.

Fig. 4 is a view taken on the line 4-4 of Fig. 3 showing a roll of gauze and means for supporting an end portion of the gauze strip that is unwound from the roll.

Fig. 5 is a view partly in section looking downwardly at the plane indicated by the line 5-5 in Fig. 3, showing cams and linkage for operating pull-out fingers which engage and pull an end portion of the gauze strip from the roll.

Fig. 6 is a fragmentary sectional view taken on the line 6-6 of Fig. 3, illustrating details of a multi-lobe cam structure for driving the gauze pull-out finger operating linkage.

Fig. 7 is a view at an enlarged scale taken on the line 7-7 of Fig. 3 showing details of an oscillatable structure for supporting and operating the gauze pull-out fingers.

Fig. 8 is a horizontal view partly in section taken approximately at the line 8-8 of Fig. 7.

Fig. 9 is a view at an enlarged scale taken on the line 9-9 of Fig. 1, showing gauze cut-01f mechanism.

Figs. 10 and 11 are respectively elevational and sectional views taken respectively at the lines 10-10 and 11-11 of Fig. 9.

The surgical sponge forming machine, of which the present mechanism comprises a part, includes a bench or table 40 having a horizontal plate-like top 41 and a plurality of legs of which one is shown at '42 in Fig. 1. A tampon forming section of the machine is indicated generally at 55 in Fig. 1 and 2, and includes coaxial vertical tubes 56 and 64. During a certain part of each cycle in the operation of the machine, the lower end of the upper tube 64 is separated from the upper end of the lower tube 56 to facilitate insertion of a gauze swatch 391 into position between these two tubes. Mechanism unimportant to the present invention is operable for periodically raising and lowering the tube 64, and when the tube 64 is lowered these tubes are adapted to ephemerally retain the swatch 391 between them while gauze picking fingers, later to be described, which have delivered the swatch to the sponge assembly section 55 are retracted for engaging and delivering a successive swatch to the sponge assembling section.

Power received into the machine through a shaft 79 is transmitted through intermeshed gears 81 and 82 to a countershaft 83. An opening 43 in the table top 41 receives a lower portion of the gear 82 so it can mesh with the gear 81. The shaft 83 which is thus constantly rotated is operable through the companion gears 495 and 496 for constantly driving a shaft 494. Companion gears 44 and 45 respectively constrained for rotation with the shaft 494 and with a shaft 393 impart constant clockwise rotation to the shaft 393 as viewed in Figs. 1 and 3.

The present mechanism is adapted to automaticallyunwind a coil 380 of a gauze stri cut suitable lengths of gauze from the strip and place the cut-01f lengths of gauze strip between the sets of upper and lower tubes of the tampon forming mechanism. The gauze roll is rotatively supported upon a rod 381 extending axially therethrough and having end portions supported in declining notches 382 in sideplates 383 of a gauze-roll-supporting frame 384 which rests upon the front right end portion of the table top 41.

The free end of the gauze strip feeds out between the side plates 383 over a feed plate 371, Figs. 3, 4 and 9, which is supported on a bar 372 to which the plate is secured by screws 373. A wire-like rod 374 pivotally supported at its ends in the side plates 383 has eccentric humps 375 which press the gauze frictionally against the plate 3'71 as the gauze passes between such rod and the plate. Notches 376 in the rear edge of the plate accommodate entry of paired fingers 386-387 for gripping an end of the gauze strip projecting rearwardly over the plate. These fingers 386-387 are for pulling the gauze strip "outwardly a predetermined distance, at which time the fingers will be stopped in their rearward motion at a position of which that represented by the letter B in Fig. 3 is representative. While the fingers are at rest and the gauze strip is held tautly between these fingers and the gauze roll 380, blades 388 and 389 of shears390, Figs. 1, 2 and 9, are operated for cutting oif the strip along a transverse section coinciding with position A in Fig. 3, thus detaching a strip of gauze having a length equal to the distance between positions A and B. This strip is then held between the two pairs of .fingers 386- 387 and immediately thereafter carried by thesev fingers rearwardly a distance to cause the center of the cut-oflf 3 strip portion (or swatch) to register with and drape over the upper end of the inner lower tube 56 of the tampon assembling mechanism. This position of a gauze swatch 391 is illustrated in Figs. 1 and 2. The pairs of fingers 386-387 will be carried rearwardly past opposite sides of the tampon assembling tube 56 incident to carrying the gauze swatch into registration with the upper end of such tube. After depositing the swatch upon the upper end of the tube 56 the fingers 386-387 will be released from the swatch and returned in an open conr dition to position A in Fig. 3 for grasping t. e fresh end of the gauze strip and commencing a new cycle pursuant to which a succeeding length of the gauze is cut off to form a swatch and fed to the tampon assembling mechanism.

- The pairs of gauze gripping fingers 336-337 are carried upon a swingable structure 392 which is pivotally mounted upon a cam shaft 393, Figs. 1 and 3. This swingable structure comprises a lower casting 394, Figs. 3, 7 and 8, having axially spaced footing portions 395 which contain bearings receiving the constantly rotating cam shaft 393. A plate 396 bolted to the front face of the casting 394 has laterally spaced uprights 397 welded thereto, Figs. 1, 3 and 7. A pair of vertically spaced short parallel links 398-399 are pivotally connected respectively with each of the uprights 397. Each link 398 is pivotally connected to its upright by a pin 400, whereas each link 399 is pivotally connected with its upright by a pivoted pin 401. The gauze engaging fingers 386 are respectively mounted on the upper sides of the upper links 399 and project forwardly therefrom. The upper gauze engaging fingers 387 are connected with and project forwardly from the lower sides of respective horizontal portions of inverted J-rod structures 402 which are pivotally connected with and carried by the back ends of the parallel links 398-399. An upper portion 403 of each inverted J-rod structure 402 is connected to a lower portion 404 thereof by a threaded member 405 which is rotatively adjustable for varying the vertical spacing of the portions 403-404 and thereby changing the time at which the fingers 386387 can be separated incident to the structure 402 being elevated. A spring 406 connected between each of the upper links 399 and an anchorage 407 on its associated upright 397 urges the fingers into their closed gauze-gripping relation.

The gauze gripping fingers 386-387 are opened by a rockable member 408 pivotally mounted on the casting 394 by a pin 409. A forwardly projecting flange 411 on the member 408 is movable upwardly against the lower ends of the rod structures 402 for displacing these rods 1 upwardly and separating the fingers when the member 408 is rocked clockwise as viewed in Fig. 3. A pair of juxtaposed cam follower rollers 412-413 rotatively carried between furcations 414 of an arm 415 on the rockable member 408 are cooperable with a cam structure 416 comprising cam members 417 and 418 which are constrained for rotation with the constantly rotating cam shaft 393.

Cam member 417 has a lobe 419 which partially conceals a similar lobe 421 on the cam member 418. The cam member 417 is mounted coaxially upon the cam member 418 and is rotatively adjustable relatively thereto for changing the distance between the rising profile 422 of the lobe 419 and the descending profile 423 of the lobe 421; see Fig. 3. When cap screws 420, Fig. 8, are loosened a plate 420a releases the cam 417 to facilitate relative rotation of the cams. Cam lobe 419 cooperates with the cam follower 412 for initially rocking the member 408 and causing the gauze engaging fingers 386-387 to separate. Subsequently the outer periphery of the lobe 421 comes into registry with the cam follower 413 and thereby retains the gauze fingers separated until such roller 413 can descend along the profile 423, the roller 412 then having been carried beyond the lobe 419.

A cam structure 424, Figs. 3, 4 and 5, together with an intervening linkage causes swinging motion to be imparted to the swingable structure 392 upon which the gauze gripping fingers are mounted. Such intervening linkage comprises a rockable multi-armed lever 425, Figs. 1, 3 and 5. One arm of this lever embodies a metal strap 426 having an arcuate end portion 427 which is connected with the pivoted casting 394 by means of an adjustable link 428 and a slider 429 which is adjustable lengthwise on said curved end portion. The radial center of the curved end portion 427 substantially coincides with a pivotal connection 431 between the upper end of the link 428 and the rockable casting 394 while the casting 394 and the lever 425 are pivoted counter-clockwise to place the fingers 386-387 at the gauze engaging position A, so that adjustment of the slider can then be made upon the curved end portion without disturbing the position of said casting and fingers.

An arm 432 of the lever 425 is bifurcated at its upper end and carries two coaxial cam follower rollers 433 and 434 for respective cooperation with cam members 435-436 of the cam structure 424. A downwardly and rearwardly projecting arm, 437, of the lever 425 is connected with one end of a contraction spring 438 which has its-upper end anchored at 439 to the table top 41. The three arms 432, 437 and 438a of the lever 425 radiate from a common hub 441 which is oscillatively mounted upon a rod 442 which is supported at opposite end portions in hanger bars 443 and 444 depending from the lower side of the table top. A portion of the strap 443 is broken away in Fig. 3 to expose the cam structure 424. Brace strap 445 anchored to the table top is connected with a lower portion of the hanger strap 443 and also with a third hanger bar 446.

Hanger bar 446 pivotally supports, at 447, a lever 443 which carries a cam follower roller 449 at its upper end for cooperation with a cam member 451 of the cam structure 424. In Figs. 5 and 6 it can be seen that the cm structure 424 includes three cams, 435, 436 and 451. A lower portion 452 of the lever 448 is curved and carries a slider 453 which is adjustable lengthwise thereof without changing the position of the lever 425 while the levers 425 and 448 are in their counter-clockwise positions at which time the pivot 455 is coincident with the radial focus of said arcuate lever portion 452. This slider is connected by a link 454 and a pivot 455 with the lower end of the arm 437.

C-arn follower 449 controls movement of the gauzegripping fingers 386-387 in their movement from position A to position B, Fig. 3. When said fingers are at position A, the short radius profile section 461 of the cam 451 will be passing beneath the follower 449 and in contact therewith. The long radius profile portion 462 of the cam member 435 will have passed (clockwise, Fig. 3) from registration with the follower 433 so that this latter follower will be suspended out of contact with any peripheral portion of the cam member 435. Likewise the cam member 436 will at this time present no profile portion in contact with its complemental follower 434. Cam lobe 421 of the cam 418, Fig. 3, will have passed (clockwise) from beneath the roller 413 to have permitted the spring 466 to close the fingers 436-487 upon the rearwardly projecting end of the gauze strip. Eventually the rise profile portion 463 of the cam 451 comes into registration with the follower 449, it passes along this follower it causes clockwise movement of the lever 448 and the consequent impartation of thrust through the link 454 for pivoting the lever 425 clockwise. This raises the link 428 and imparts clockwise motion to the casting 394 about the cam shaft 393. As a consequence of this clockwise movement of the casting 394 and the structure 392 the gauze-gripping fingers 386-387 will reach the position B when the fixed long-radius profile portion 464 of the earn 451 reaches registration with the follower 449, whereupon the rearward movement of the fingers is interrupted. During this quiescent period and as of the fingers 386-387 the shears 390, Figs. 1, 2 and 9, will be operated for cutting off the pulled-out portion of the gauze strip.

At this time it should be noted that the distance of point B from the point A is selectively varied by changing the position of the slider 453 on the arcuate lever section 452. If a longer piece of gauze is desired to be cut from the gauze strip, the position B will be shifted rearwardly by moving the slider 453 downwardly toward the free end of the curved lever portion 452. Should a shorter piece of gauze be desired, the slider 453, wiil be adjusted in the opposite direction. This adjustment of the slider 453, of course, has no influence upon the position of the associated cam follower 449 with respect to the cam 451 cooperable therewith. Therefore, irrespective of the position of the slider 453 and the consequential position of the gauze-gripping fingers from the position A for determining the length of the piece of gauze to be cut from the main strip, this desired length of gauze piece will be pulled out and the fingers 386-387 will stop in their rearward movement at the selected position B when the cam follower 449 first reaches the constant radius profile 464 of the cam 351. Thus the timing of the machine is not affected by changing the position of the slider 453, wherefore the outoif shears 398 for the gauze will be operated in proper timed relation with the gauze pull out mechanism so the shearing operation takes place while the fingers 386-387 are at rest.

While the constant radius profile section 464 is passing under the follower 449, and subsequent to the operation of the gauze shears 399, a curved profile 465 of the cam member 436 will be carried into contact with the cam follower roller 434 and thereby commence to pivot the lever 425 in a clockwise direction. This pivoting of the lever 425 is also opposed by the spring 438, and during such clockwise pivoting of the lever 425 by the cam profile 465 and the follower 434 the link 454 will cause pivoting of the lever 448 for lifting the follower 449 from the cam member 451. Rearward movement of the fingers 386-387 is therefore resumed by virtue of force received from the cam profile 465 by the cam follower 434 and until the longer radius profile portion 462 of the cam 435 comes into registry with the follower 433. At this time the fingers 386-387 will be disposed rearwardly of the tampon assembling mechanism tubes 56 and 64, as illustrated in Fig. 1. It is desired for the fingers 386-387 to move rearwardly a distance for causing the center of the gauze piece to register axially with the tubes 56 and 64. Such registration is incurred by moving the slider 429 along the curved lever section 427. When a longer gauze piece has been cut from the strip, it will be necessary for the fingers 386-387 to move rearwardly a greater distance for bringing the center of this piece into coaxial relation with the tubes 56 and 64, and this is accomplished by moving the slider 429 outwardly of the lever curved section 427. A shorter gauze piece will involve adjustment of the lever slider 429 in the opposite direction.

Substantially simultaneously with arrival of the gauze strip into registration with the tampon assembling mechanism 55 the rise profile portion 422 of the cam lobe 419, Fig. 3, will overtake the follower 412, and the lobe 419 will pass into registration with such follower for releasing the fingers 386-387. Control of the gauze piece 391 is transferred to the tampon assembling mechanism this time by downward movement of the tube 64, Figs. 1 and 2, which thereby cooperates with the upper end of the tube 56 for preventing accidental displacement of the gauze piece after it is released by the fingers 386-387 and during the retrograde movement of these fingers which ensues.

immediately after the long radius profile portion 462 of the cam member 435 passes from registration with the roller 433, a descending profile portion 466 of such cam member commences to cooperate with the cam follower roller 433 to control counterclockwise motion of the levers 448 and 425 by the force imparted thereto by the spring 438. Such counter-clockwise movement of the levers 448-425 causes the aforesaid retrograde movement of the gauze-engaging fingers 386-387. During this retrograde motion of the fingers 386-387 they are held apart first by the cam lobe 419 in registry with the follower roller 412 and subsequently by the cam lobe 421 cooperatively with the follower 413. The descending profile portion 423 of the lobe 421 passes beneath the roller 413 and allows the fingers to close upon their being returned to position A, so that when the fingers do close they will establish a gripping relation with the leading edge of the gauze strip preparatory to pulling the strip rearwardly pursuant to performance of the succeeding operating cycle. When the fingers 386-387 have been returned to position A, the short radius profile section 461 of the cam member 451 will again be in registry with the cam follower 449, and the rise profile portion 463 of this cam member will be approaching said follower preparatory to displacing the same for moving the fingers from position A to position B in starting the succeeding operating cycle.

Proper timing of the opening of the gauze-gripping fingers 386-387 while they are in the position illustrated in Fig. 1 can be attained by adjusting the cam member 417 rotatively about the shaft 393 so that the cam lobe 419 can be caused to pass beneath the roller 412 in sufficient time to release the gauze piece 391 before the fingers are moved forwardly from the tampon assembling mechanism 55, and also to avoid premature opening of the fingers so the gauze piece cannot move out of registry with the mechanism 55 prior to such gauze piece being grasped between the tubes 64 and 56, Fig. 1.

In Figs. 3, 5 and 6 it can be seen that the cam member 436 is mounted uponthe cam member 435 by means of a pivot support 471. A threaded end portion 472 of this support screws into a threaded hole 473 in the cam member 436, and a set screw 474 resists relative rotation of the members 471 and 436. In Fig. 3 a pair of faces 475-476 can be seen upon the cam member 436 for respective engagement with set screws 477-478 carried by the cam member 435. By loosening the set screw 474, and one of the set screws 477 or 478 and tightening the other of the screws 477 or 478, the radial position of the cam profile 465 on the member 436 can be varied and thereby cause it to effect an initial gradual pressure relation with its cooperative cam follower roller 434. When this position of the cam profile 465 has been determined, each of the set screws 474-477-478 will be tightened for maintaining the adjustment.

The gauze cutting shears 390 are mounted by means of their pivot pin 481 upon a bracket 480, Figs. 1, 9, 10 and 11, which is secured to one of the gauze frame plates 383. Operation of the shears is effected through a pair of links 482 and 483 which are respectively pivotally connected to the shear blades 388-389 at 484-485. The lower ends of these links are pivotally connected with arms 486-487 extending generally oppositely from a rockable hub 488 rockably disposed on a headed bearing pin 489 anchored in a bearing bracket 490. In Fig. 9 the shears are shown with their blades closed, but rocking of the hub 488 clockwise will cause the link 482 to be pulled downwardly and the link 483 to be thrust upwardly for separating the shear blades to the dotted line positions.

A spring 491 urges the hub 488 to turn counter-clockwise and thereby presses a cam follower roller 492 against the profile of a cam 493 which is constrained for rotation with a shaft 494. Shaft 494 is constantly rotated, it being driven by mated bevelled gears 495-496 respectively upon the shafts 83 and 494, Figs. 1 and 9. Said shaft 494 is supported in bearing blocks 497-498, Fig. 1. Once during each revolution of the cam 493 the follower 492 will register with the middle portion of a straight profile portion 501 of the cam and thereby permit the spring 491 to close the shears for cutting oif a piece of gauze while the gauze-gripping fingers 386-387 are at rest in position B of Fig. 3. Subsequent to the cutting off of the gauze piece, a profile point 502 will approach the cam follower 492 and cause the shears to be opened. They will remain open while the circular long radius profile portion 503 passes under the follower and the shears will not commence to close until cam profile point 504 again passes beneath the follower.

Having described a single preferred embodiment of the invention with the view of clearly and concisely illustrating the same, I claim: 7

1. Strip pull-out and feeding mechanism comprising an excursively movable gripping means support; strip gripping means mounted on said support for movement therewith; and means for moving said support and the gripping means thereon including a cam structure, a plurality of cam followers connected with said support for imparting movement thereto in one direction, and profile means on the cam structure cooperable with one of said followers to impart movement to the support and gripping means in one direction and subsequently cooperable with the other follower to resume such movement.

2. Strip pull-out and feeding mechanism comprising strip gripping means pivotally movable excursively from one position and back to the one position; and means for incurring the excursive movement of said gripping means including a rockable structure having an arcuate attaching portion eccentric to the axis about which said structure is rockable, means for rocking said structure between relatively advanced and retracted positions, a link extending between a pivotal connection with said gripping means eccentrically of its pivot axis and a pivotal connection with the arcuate portion of the rockable structure to transmit operating force therebetween, said link being adapted to'place the gripping means in its one position pursuant to the rocking of said structure into its retracted position and to place the gripping means in its other position pursuant to rocking of said structure into its advanced position, the connection of the link with said arcuate portion of the rockable structure being adjustable linearly of such portion to selectively change said other position of the gripping means, and said arcuate portion being disposed concentrically of the pivotal connection of the link with the gripping means while such gripping means is at its one position wherefore such linear adjustment avoids shifting said one position of the gripping means.

3. Strip pull-out and feeding mechanism comprising strip gripping means movable excursively from one position and back to the one position; and means for incurring the excursive movement of said gripping means including a rockable structure having an arcuate attaching portion eccentric to the axis about which said structure is rockable, said structure being rockable between relatively advanced and retracted positions, a link extending between a pivotal connection with said gripping means and a pivotal connection with the arcuate portion of the rockable structure to transmit operating force therebetween, said link being adapted to place the gripping means in its one position pursuant to the rocking of said structure into its retracted position and to place the gripping means in its other position pursuant to rocking of said 8 structure into its advanced position, the connection of the link with said arcuate portion of the rockable structure being adjustable linearly of such portion to selectively change said other position of the gripping means and said arcuate portion being disposed concentrically of the pivotal connection of the link with the gripping means while such gripping means is at its one position wherefore such linear adjustment avoids shifting said one position of the gripping means, means for rocking said structure part way from its retracted position toward its advanced position to place the gripping means at a position intermediate its one and other positions including a pivotal lever having an arcuate portion eccentric of the pivot of such lever, a second link extending between a pivotal connection with the rockable structure and a pivotal connection with the arcuate lever portion, said second link being adapted to rock the rockable structure to place the gripping means at the intermediate position pursuant to pivotal movement of the lever from a retracted position into a more advanced position, means for so pivoting the lever, other means for subsequently rocking the rockable structure into its advanced position, the pivotal connection of the second link being adjustable linearly of the lever arcuate portion, the arcuate lever portion being eccentric of the pivotal connection of the second link with the rockable structure while the lever is in the more advanced position wherefore adjustment of said pivotal connection thereon changes the rocked position of the rockable structure to selectively change the intermediate position of the gripping means, and the arcuate lever portion being concentric of the connection of the second link with the rockable structure while the lever and structure are retracted wherefore such adjustment linearly of the curved lever portion avoids disturbance of the one position of the gripping means.

4. The combination set forth in claim 3, wherein the rockable structure and the lever are pivotal about parallel axes, and wherein the means for pivoting the lever comprises cam means rotatable about axes parallel with said axes and a cam follower interposed between the cam means and the lever to pivot such lever into its advanced position, and wherein the other means for rocking the structure comprises a second cam follower interposed between the cam means and the rockable structure for rocking the same into its advanced position, and the cam means operating the folowers in a sequence that the second follower rocks the rockable structure subsequent to a time interval following said pivoting of the lever whereby the gripping means has a period of quiescence at its intermediate position.

References Cited in the file of this patent UNITED STATES PATENTS 464,952 Becker Dec. 15, 1891 763,195 Merz June 21, 1904 1,341,184 Leumann Mar. 25, 1920 1,392,871 Heffelfinger Oct. 4, 1921 1,825,821 Rosenthal Oct. 6, 1931 1,826,498 Bignell Oct. 6, 1931 2,228,245 Barker et al. Jan. 14, 1941 2,406,784 Almgren Sept. 3, 1946 

